JP4296967B2 - Communications system - Google Patents

Description

  The present invention relates to a communication system having excellent noise resistance and suitable for industrial use in which a plurality of communication devices are connected.

Conventionally, in the industrial field, noise generated due to motor driving is large, so in communication between devices, there is often an error in packet data transmitted due to this noise, and if an error occurs, it is the sender It has been common to perform normal packet data retransmission processing from a communication device (see, for example, Patent Document 1).
JP-A-10-276198

  The problem to be solved is that retransmission processing performed to repair a data error that occurred during packet data transmission causes a delay in packet data transmission. In other words, the retransmission process causes a transmission delay for at least one communication cycle, which is a fatal problem for industrial applications that require real-time performance. In particular, in ring connection communication, the error rate of packet data increases in proportion to the communication loop path length.

  The present invention solves the above-described problems, and an object of the present invention is to provide a communication system excellent in noise resistance and real-time performance that can be used even in a poor environment.

In order to solve the above-described problem, the present invention provides a communication system in which a master device and a plurality of slave devices are sequentially connected by ring connection, and the master device that is a transmission source is configured for each slave device from command data in a transmission buffer. A packet that extracts the divided data block A1 group, duplicates a specified number of identical data blocks B1 for all the data blocks A1 group, and generates packet data P1 in which these are arranged in a specified order A data generation unit, and a code addition unit that inputs the packet data P1 and generates a signed packet data to which an error detection code is added, and transmits the signed packet data from the transmission unit to the reception unit of the slave device The slave device adds the signed packet data received by the receiving unit for each data block. An error detection unit for detecting a data error from an error detection code, a reception data extraction unit for transferring a valid data block C without data error to a reception buffer, and an effective data block transferred from the reception data extraction unit The group C is a data block A2 group, the data block B2 group identical to the data block A2 group is duplicated by a specified number, and packet data P2 in which these data blocks are arranged in a specified order is generated. A packet data generation unit for adding response data and its duplicate data from the transmission buffer, and a code addition unit for adding an error detection code to each data block output from the packet data generation unit. Further includes all of the packet data P2 and the response data and its duplicated data. A function of generating packet data P3 in which data blocks are rearranged in a prescribed order, and the code adding unit generates signed packet data P4 to which an error detection code is added for every data block in the packet data P3, By transmitting data from the transmitter to the receiver at the other end, it is possible to detect errors for each data block. Even if a data error occurs due to noise in a data block, it is effective from the duplicated data block. It is possible to extract and reproduce the correct data.

According to the communication system of the present invention, it becomes possible to reproduce the error detection of the packet data for each slave equipment which is ring connected, in a connection unit of each communication device, it is replicated with the original data block As long as no error occurs in all data blocks, it is possible to eliminate retransmission of normal packet data. For this reason, the error occurrence rate in packet data transmission in units of communication loop paths is greatly reduced, the occurrence rate of defects requiring retransmission processing can be greatly reduced, and real-time performance can be ensured.

In a communication system in which a master device and a plurality of slave devices are sequentially connected by ring connection, a master device that is a transmission source extracts a data block A1 group divided for each slave device from command data in a transmission buffer, A packet data generator for generating a packet data P1 in which a specified number of identical data blocks B1 are copied for all the data blocks A1 in a specified order, and the packet data P1 is input. And a sign adding unit that generates signed packet data to which an error detection code is added, and transmits the signed packet data from the transmitting unit to the receiving unit of the slave device. Data errors are detected from the error detection code added to each data block in the received signed packet data. An error detecting unit, a received data extracting unit for transferring a valid data block C free of data errors to a receiving buffer, and a valid data block C transferred from the received data extracting unit as a data block A2 group. , The same number of the same data block B2 group as the data block A2 group is duplicated by a specified number, packet data P2 in which these data blocks are arranged in a specified order is generated, and response data from its own transmission buffer is generated. And a packet data generation unit for adding the duplicate data, and a code addition unit for adding an error detection code to each data block output from the packet data generation unit, the packet data generation unit further including packet data P2 and Rearrange all data blocks of response data and its duplicated data in the prescribed order The packet adding unit generates a signed packet data P4 in which an error detection code is added to every data block in the packet data P3 by the code adding unit. , It is possible to detect errors for each data block. Even when a data block is affected by noise and a data error occurs, valid data is extracted from the copied data block and reproduced. It becomes possible.

  FIG. 1 shows a block diagram of a ring-connected communication system, in which a transmission unit 030 of a communication device 010 and a reception unit 041 of a communication device 011 are connected by a communication cable 050 and packet data transmitted from the communication device 010 is transmitted. Is received by the communication device 011. Then, sequentially, the transmission unit 031 of the communication device 011 and the reception unit 042 of the communication device 012 are connected by the communication cable 051, and similarly, the communication device 012, the transmission unit 032 and the reception unit 043 of the communication device 013 are connected by the communication cable 052, and communication. The transmission unit 033 of the device 013 and the reception unit 040 of the communication device 010 are connected by the communication cable 053, and the communication device 010 receives the packet data transmitted from the communication device 013.

  When n + 1 communication devices are ring-connected, the transmission unit 03n of the communication device 01n connected finally to the reception unit 040 of the communication device 010 is connected by the communication cable 05n and transmitted from the communication device 01n. The communication device 010 receives the packet data to be processed.

Next, a description will be given of an example of a master-slave type communication system in which the communication device 010 is a master and the communication devices 011, 012, and 013 are slaves and is ring-connected. An example of processing when this communication system is affected by noise and a data error occurs in the middle will be sequentially described with reference to FIGS.

  First, the packet data generation unit 080 divides the data in the transmission buffer 060 of the master communication device 010 into three data blocks MD1, MD2, and MD3. For example, MD1, MD2, and MD3 are command data from the master to the slave corresponding to the respective communication devices 011, 012, and 013.

  The packet data generation unit 080 generates a data block that is duplicated one by one for all of these data blocks, and inputs the data blocks arranged in a prescribed order to the code addition unit 090 to generate an error. Signed packet data 120 is generated in which data blocks MDA1, MDB1, MDA2, MDB2, MDA3, and MDB3 to which detection codes are added are arranged in a prescribed order. Here, the data blocks MDA1, MDB1, MDA2, MDB2, MDA3, and MDB3 are arranged in this order. Further, it is supplemented that the data blocks MDA1 and MDB1, MDA2 and MDB2, and MDA3 and MDB3 are completely identical data blocks (upper part of FIG. 2).

  Next, the signed packet data 120 is transmitted from the transmission unit 030 of the communication device 010 to the reception unit 011 of the communication device 011. Assuming that noise is applied to the communication cable 050, a data error has occurred in the transmitted signed packet data 120, and this has been changed to signed packet data 121, this signed packet data 121 is received by the receiving unit of the communication device 011. Received at 041.

  The packet data 121 is transferred from the receiving unit 041 to the error detecting unit 101, and it is checked whether there is an error for each data block. Here, it is assumed that an error has occurred only in the data blocks MDB1 and MDA2 (bottom in FIG. 2).

  First, since there is no error in the data block MDA1, MDA1 is validated. Next, since there is an error in the data block MDA2, the data of the duplicate MDB2 is made valid. Finally, since there was no error in MDA3, this MDA3 is validated, and MD1, MD2, and MD3 are extracted from the data blocks determined to be valid by the reception data extraction unit 111 and transferred to the reception buffer 071. Forward to part 081.

  The packet data generation unit 081 of the communication device 011 generates data blocks that are duplicated one by one for all the data blocks transferred from the reception data extraction unit 111, and arranges these data blocks in a prescribed order. To do.

  Further, the data block SD1 in the transmission buffer 061 is transferred to the packet data generation unit 081. For example, SD1 is response data from the communication device 011 to the communication device 010.

  Next, the packet data generation unit 081 duplicates the data block SD1 and puts all these data blocks including the data block already transferred from the received data extraction unit 111 in a prescribed order to the code addition unit 091. The signed packet data 122 in which the data blocks MDA1, MDB1, MDA2, MDB2, MDA3, MDB3, SDA1, and SDB1 to which the error detection codes are added is arranged in a prescribed order is generated. Here, the data blocks MDA1, MDB1, MDA2, MDB2, MDA3, MDB3, SDA1, and SDB1 are arranged in this order. Further, it is supplemented that the data blocks SDA1 and SDB1 are exactly the same data block (FIG. 3).

Next, the signed packet data 122 is transmitted from the transmission unit 031 of the communication device 011. Assuming that noise is applied to the communication cable 051, a data error occurs in the transmitted signed packet data 122, and the signed packet data 123 is changed to the signed packet data 123, and this signed packet data 123 is received by the receiving unit 042 of the communication device 012. Receive. Further, the packet data 123 is transferred to the error detection unit 102, and it is checked whether there is an error for each data block. Here, the error occurs only in the data blocks MDB 2 and SDA1.

  The processing in the communication device 012 is performed in the same manner as the communication device 011. This process will be described with reference to FIG. In this case, MDA1, MDA2, and MDA3 are valid, and MD1, MD2, and MD3 are extracted from the data blocks determined to be valid by the reception data extraction unit 112 and transferred to the reception buffer 072 and the packet data generation unit 082. Since SDA1 has an error, SDB1 is validated, SD1 is extracted, and transferred to the packet data generation unit 082.

  Further, the data block SD2 in the transmission buffer 062 is transferred to the packet data generation unit 082. For example, SD2 is response data from the communication device 012 to the communication device 010.

  Next, the packet data generation unit 082 duplicates the data block SD2, and puts all these data blocks including the data block already transferred from the received data extraction unit 112 in a prescribed order to the code addition unit 092. The signed packet data 124 in which the data blocks MDA1, MDB1, MDA2, MDB2, MDA3, MDB3, MDB3, SDA1, SDB1, SDA2, and SDB2 to which error detection codes are added is arranged in a prescribed order is generated. The packet data 124 is transmitted from the transmission unit 032 to the reception unit 043 of the communication device 013.

  By performing the processing in the communication device 013 in the same manner as the communication devices 011 and 012, the communication device 010 finally receives the signed packet data 127 shown in FIG. 5 and the error detection unit 100 and the reception data extraction unit 110 perform slave processing. The valid response data SD1, SD2, and SD3 from the communication devices 011, 012, and 013 can be extracted to the reception buffer.

  In other words, even if a data error occurs due to the influence of noise on each transmission path between the communication device apparatuses, it is possible to reproduce the data block for each received communication apparatus, and the data copied with the original data block Unless there is an error in the block at the same time, normal packet data retransmission is unnecessary.

  As a result, even in ring-connected communications, where there is a problem that the packet data error rate increases in proportion to the communication loop path length, the error rate in packet data transmission in units of communication loop paths significantly decreases. Therefore, the occurrence rate of defects requiring retransmission processing can be greatly reduced, and real-time performance can be ensured.

  In the second embodiment, when the signed packet data 123 received by the communication device 012 in the first embodiment is neither MDA2 nor MDB2 valid as shown in FIG. 6, that is, the original data block and the duplicated data block Shows an example of processing when errors occur simultaneously.

MDA2 and MDB2 were command data from the communication device 010 as the master to the communication device 012 as the slave, but the communication device 012 could not normally receive this, so the block data SDA2 and SDB2 created from the transmission buffer 062 Instead, data blocks ERA2 and ERB2 indicating that an error has occurred are arranged in the packet data 124.

  When the signed packet data 127 finally received by the communication apparatus 010 has a value as shown in FIG. 7, the data block ER2 indicating that an error has occurred is extracted to the reception buffer 070. From this data block ER2, the communication device 010 can recognize that the communication device 012 has not normally received the block data MD2. As an example of processing of the communication device 010 in this case, similar command data is transmitted again only to the data block of the communication device 012 or the communication processing itself is stopped.

  Further, since the data block division unit is the communication device unit, only the communication device 012 has not been successfully received, and the communication devices 011 and 013 have normally received the command from the communication device 010. A response can be returned normally. Therefore, the communication device 010 does not need to retransmit the entire packet data, and can improve real-time performance.

In particular, when the noise environment is inferior, the error occurrence rate of packet data can be increased by increasing the number of data block duplications to two or more as shown in FIG. For example, even if an error occurs in both the data blocks MDA2 and MDB2, if there is no error in the data block MDC2 which is another copy of the data blocks, the block data MD2 can be reproduced and real-time performance can be improved. It becomes.
(Reference Example)

As a reference embodiment, a communication system in which a plurality of communication devices are connected by bus will be described. FIG. 9 is a block diagram of a master-slave communication system in which the communication device 210 is a master and the communication device 211 and the communication device 212 are slaves. Packet data is transmitted from the transmission unit 230 of the communication device 210 to the communication cable 250. Communication device 211 and communication device 212 connected via bus disable use of transmission unit 231 and transmission unit 232 and enable reception unit 241 and reception unit 242 to receive packet data. .

  An example of processing when this communication system is affected by noise and a data error occurs in the middle will be described with reference to FIGS.

  Data in the transmission buffer 260 of the communication device 210 as a master is divided into two data blocks MD1 and MD2 by the packet data generation unit 280. For example, MD1 and MD2 are command data from the master to the slave corresponding to the respective communication devices 211 and 212.

  The packet data generation unit 280 generates data blocks that are duplicated one by one for all of these data blocks, and inputs these data blocks arranged in a prescribed order to the code addition unit 290 for error detection. Signed packet data 320 is generated in which data blocks MDA1, MDB1, MDA2, and MDB2 to which codes are added are arranged in a prescribed order. Here, the data blocks MDA1, MDB1, MDA2, and MDB2 are arranged in this order (upper part of FIG. 10). Further, it is supplemented that the data blocks MDA1 and MDB1 and MDA2 and MDB2 are the same data blocks.

Next, the signed packet data 320 is transmitted from the transmission unit 230 of the communication device 210. It is assumed that noise is applied to the communication cable 250 and a data error occurs in the transmitted signed packet data 320, which changes to signed packet data 321 and signed packet data 322. The signed packet data 321 is converted into the communication device 211. Are received by the receiving unit 241, and the signed packet data 322 is received by the receiving unit 242 of the communication device 212.

  Further, the packet data 321 is transferred to the error detection unit 301 of the communication device 211 and the packet data 322 is transferred to the error detection unit 302 of the communication device 212 to check whether there is an error for each data block. Here, it is assumed that the error detection units 301 and 302 both detect errors in the data blocks MDB1 and MDA2. In the communication apparatus 211, since there is no error in the data block MDA1, MDA1 is validated.

  Next, since there is an error in the data block MDA2, the data in the duplicate MDB2 is validated, and the data MD1 and MD2 are extracted from the data block determined to be valid by the reception data extraction unit 311 and stored in the reception buffer 271. Transfer (in FIG. 10). Similarly to the communication apparatus 211, the communication apparatus 212 transfers MD1 and MD2 to the reception buffer 272 (lower part in FIG. 10).

  Next, an example in which the communication apparatus 211 can transmit data will be described using FIG. 9 and FIG. 11 together. The data block SD1 in the transmission buffer 261 of the communication device 211 is transferred to the packet data generation unit 281. For example, SD1 is response data from the communication device 211 to the communication device 210.

  Next, the packet data generation unit 281 duplicates the data block SD1, inputs the data blocks SD1 arranged in a prescribed order to the code adding unit 291, and adds the data block SDA1 to which the error detection code is added. Signed packet data 323 in which SDB1 is arranged in a prescribed order is generated. Here, the data blocks SDA1 and SDB1 are arranged in this order. Further, it is supplemented that the data blocks SDA1 and SDB1 are exactly the same data block (upper part of FIG. 11).

  Next, the signed packet data 323 is transmitted from the transmission unit 231 of the communication device 211. Assuming that noise is applied to the communication cable 250, a data error occurs in the transmitted signed packet data 323, and this is changed to signed packet data 324 and signed packet data 325. The data is received by the receiving unit 240 of the communication device 210, and the signed packet data 325 is received by the receiving unit 242 of the communication device 212. Further, the signed packet data 324 is transferred to the error detection unit 300 of the communication device 210 and the packet data 325 is transferred to the error detection unit 302 of the communication device 212 to check whether there is an error for each data block. Here, it is assumed that the error detection unit 300 and the error detection unit 302 both detect an error in the data blocks MDB1 and MDA2 (lower in FIG. 11).

In communication device 210, data block SDA1 has no error, so SDA1 is validated. Data SD1 is extracted from received data block 310 by received data extraction unit 310 and transferred to reception buffer 270. Even if a data error occurs due to noise in each of the transmission paths, normal packet data retransmission can be made unnecessary unless an error occurs simultaneously in the original data block and the duplicated data block. Therefore, the error occurrence rate in packet data transmission is greatly reduced, the failure occurrence rate requiring retransmission processing can be greatly reduced, and real-time performance can be ensured.

The communication apparatus according to the present invention is inferior in that noise occurs frequently because the repaired data is transmitted to the next path even if an error occurs in the data on a certain path and the retransmission from the master apparatus is unnecessary. This is useful for industrial applications that require real-time performance regardless of the environment, especially when many slave devices are connected by ring connection.

The block diagram of the communication system in Example 1 and Example 2 of this invention Explanatory drawing of the packet data reproduction example 1 in Example 1 of this invention Explanatory drawing of the packet data reproduction example 2 in Example 1 of this invention Explanatory drawing of the packet data reproduction example 3 in Example 1 of this invention. Explanatory drawing of the packet data reproduction example 4 in Example 1 of this invention. Explanatory drawing of the packet data reproduction example 1 in Example 2 of this invention Explanatory drawing of the packet data reproduction example 2 in Example 2 of this invention. Explanatory drawing of the packet data reproduction example 3 in Example 2 of this invention. Block diagram of a communication system in a reference embodiment of the present invention Explanatory drawing of the packet data reproduction example 1 in the reference embodiment of the present invention Explanatory drawing of the packet data reproduction example 2 in the reference embodiment of the present invention

Explanation of symbols

010 to 013 Communication device 030 to 033 Transmission unit 040 to 043 Reception unit 050 to 053 Communication cable 060 to 063 Transmission buffer 070 to 073 Reception buffer 080 to 083 Packet data generation unit 090 to 093 Code addition unit 100 to 103 Error detection unit 110 ˜113 Received data extraction unit 120˜127 Signed packet data 210˜212 Communication device 230˜232 Transmission unit 240˜242 Reception unit 250 Communication cable 260˜263 Transmission buffer 270˜273 Reception buffer 280˜283 Packet data generation unit 290˜ 293 Code addition unit 300 to 303 Error detection unit 310 to 313 Received data extraction unit 320 to 325 Signed packet data

Claims (2)

In a communication system in which a master device and a plurality of slave devices are sequentially connected by ring connection, a master device that is a transmission source extracts a data block A1 group divided for each slave device from command data in a transmission buffer, A packet data generator for generating a packet data P1 in which a specified number of identical data blocks B1 are copied for all the data blocks A1 in a specified order, and the packet data P1 is input. And a sign adding unit that generates signed packet data to which an error detection code is added, and transmits the signed packet data from the transmitting unit to the receiving unit of the slave device. Data errors are detected from the error detection code added to each data block in the received signed packet data. That an error detection unit, and a reception data extracting unit to forward the no data error valid data block group C to the receiving buffer, the valid data block C group data blocks transferred from the reception data extracting unit A2 A group of data blocks B2 that are identical in number to the data block A2 group are copied by a specified number, and packet data P2 in which these data blocks are arranged in a specified order is generated. A packet data generation unit that adds response data and its duplicate data; and a code addition unit that adds an error detection code to each data block output from the packet data generation unit. The packet data generation unit further includes packet data relocate all data blocks of the copy data and P2 and response data to the prescribed sequence Having a function of generating a packet data P3, the sign adding section generates the signed packet data P4 obtained by adding an error detection code for every data block in the packet data P3, the receiver of the destination from the transmission unit Communication system to transmit to . The packet data generation unit of the slave device in which both the original data and the duplicated data of the packet data P2 are not valid adds error data indicating the occurrence of an error instead of the response data, and the master device uses the error data to indicate the slave data. The communication system according to claim 1, wherein the apparatus recognizes that reception has failed .

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